Rotary-grate burner



Aug. 26, 1947. w; M. FULT.OIN ET AL 'ROTARY-G-RATE BURNER Filed July 27, 1944 3 Sheets-Sheet l Aug. 26, 1947- w. M. FULTON El AL I I ROTARY-GRATE BURNER Filed July 27; 1944 3 Sheets-Sheet 3 Patented Aug. 26, 1947 ROTARY-GRATE BURNER Weston M. Fulton and Sidney R. Galyon, Knoxville, Tenn., minors to W. 1. Savage Company, Inc., Knoxville, Tenn., a corporation oi.

Tennessee Application July 27, 1944, Serial No. 548,770

4 Claims. 1

This invention relates to an improvement in rotary-grate burners, of the character set forth in the co-pendlng application of Weston M. Fulton, on Burners for solidfuels, Serial No. 546,771, filed July 27, 1944.

In the above-mentioned application, and also an earlier application of Weston M. Fulton, Serial No. 535,848, filed May 16, 1944, a fire-clay baffle was used in the upper part of a rotary burner to furnish a hot surface against which the gaseous products of combustion impinge upon rising from the fire bed. Where such a fire-clay bafile is used in association with rotary grate-bars of the type set forth in the above-mentioned application of Weston M. Fulton, for.Burners for solid fuels, Serial No. 546,771, such a fire-clay baifle would not efiectively support the grates during a portion of their travel in the upper region of their orbit and would also have a tendency to heat the grates, whereas it is desirable that they be cooled as much as possible.

The object of this invention is to improve the character of the baii'ie' used in a rotary-grate burner to enable it to be water-cooled, whereby such a baiiie may support the grates during this portion of their travel while also cooling them in this region. Such a water-cooled bailie is interposed between the grates in their upper region and the fire bed in the burner so as to insulate the grates from the heating eiiect of the fire bed at this upper region, thereby tending to cool the grates.

The invention is shown as applied to a rotarygrate burner in the accompanying drawings, in which:

Fig. 1 is a side elevation of the burner;

131g. 2 is a vertical cross-section therethrough; an

Fig. 3 is a longitudinal section therethrough on the line 2-2 of Fig.2.

In the form of the invention illustrated in the drawings, the burner comprises two main parts designated respectively at I and 2, each of which is constructed substantially of annular form and mounted in stationary position against rotation. The parts I and 2, being elongated horizontally, form an enclosed hollow non-rotating shell extending about the rotating grates mounted therein.

The burner part I is formed with an outer wall within opposite ends of the burner part I, and v I 2 I (see Figs. 2 and 3), an inner wall 4 and end walls 5 and 8, enclosing therehetween an annular space or water chamber 1. This annular space I is adapted to be filled with water or other cooling medium which may besupplied thereto by convectional circulation from the boiler to which the burner is attached in a manner similar to that described in the prior application on Fuel burners for boilers, Serial No. 529,502, filed April 4, 1944, as hereinafter referred to more in detail.

In a similar manner, the part 2 has an outer wall 5, an inner wall 9, and end walls l0 and ii, enclosing an annular space I2 which is adapted to be filled with water in the samemanner and from the same source as described above in connection with the burner part I.

The burner parts I and 2 are formed with air chambers l8 and 22 in the lower portions thereof,

which are open to the peripheries of these burner parts through slots 20 and 24, respectively.

Mounted on one side and near the bottom of the burner, as shown in Fig. 1,,is a wind-box 25 which extends throughout the major portion of the length of the burner, including the parts I and 2, enclosing therein the slots 20 and 24, as ,will be evident from Figs. 1 and 3. The wind-box 25 is adapted to supply air to these slots, as indicated by the arrows in Figs. 2 and 3. An air duct 28 extends to the wind-box 25 from a blower 21 for supplying air, as needed, to the wind-box, which in turn directs it into the burner, as described.

At the interior of the burner part I is a series of grate-bars 28, each of which is formed slightly arcuate in cross-section, as shown in Fig. 2, and has beveled opposite edges 28. The opposite ends of the gate-bars 28 are loosely interconnected with driving rings 3i and 32 (Fig. 3), each of which is notched at its inner edge to receive an end of the grate-bar therebetween. The driving rings 2i and 22 are mounted to rotate freely move the grate-bars through an orbit substantially in contact with the inner wall 4 throughout the, major portion of the circumference of the burner part I, but with the grate-bars slightly spaced from each other leaving longitudinal slots or openings 28 therebetween, as shown in Fig. 2.

Each of the driving rings ill, 32 has ratchet teeth 21 on its peripheral portion thereof, in the illustrated embodiment of the invention, as means of rotat g the rings and grate-bars. The bu er part 2 is provided also with a driving ring 59, which is similar to the rings 9i and 32, except that it extends continuously throughout the width of the burner part 2 and has an inwardly disposed annular rim 40 at the inner end of the burner. Furthermore, the driving ring 89 has ratchet teeth 4I on its peripheral rim portion, but of shorter pitch than the ratchet teeth 81 so as to provide for finer stepping adjustment of the driving ring 99, than of the driving rings 3|, 32. The driving ring 39 has elongated openings or slots therein, loosely receiving grate-bars 43 which are sufllciently loose in the openings to permit inward movement of the grate-bars and also to allow spaces therearound for the passage of air from the chamber 22 into the interior of the burner to support combustion.

At the fuel inlet end of the burner is a stationary burner head 45 (Fig. 3), which forms an enclosure for the cylindrical burner structure. The burner head 45 is hollow to provide a water space 46 therein, and having inlet and outlet water connections at its bottom and top respectively, each of which is provided with a push nipple, one being shown at 48 at the top, as a means of connecting the burner head with the burner part I. These connections permit free circulation of water between the water chamber 45 in the burner head and the water chambers I and I2 in the burner parts I and 2 in a manner usually employed in the construction of cast iron boilers.

One end of the cylindrical burner is supported by means of the burner head 45, which is carried by legs 49 on a base 50, preferably bolted thereto. The opposite end of the burner may be supported in any convenient manner, but we prefer that it be seated in a fire-brick wall i (Fig. 1) which connects the outlet end of. the burner with a heating boiler 52. The fire-brick wall BI has a chamber 53 therein, receiving the products of combustion from the burner and having a fire-brick face in opposed relation to the open end of the burner.

When the burner parts I and 2 are assembled together with the burner head 45, they constitute an integral non-rotating enclosure for the rotating grates. One end of this enclosure is connected with the furnace structure including the fire-brick wall on which the enclosure is mounted. Hence, it is only necessary to support separately the opposite end of the structure.

The burner head 45 is provided also with the fuel inlet 54 opening into the inner side of the burner at a point preferably located at the vertical longitudinal plane through the axis of the burner, and preferably above the axis. This fuel inlet is preferably in the form of a zigzag conduit through which the fuel may be directed into the outer end of the burner from a suitable source of fuel supply, such as a hopper.

Referring to Fig. 1, the rotor of the blower 21 is keyed on the armature shaft of an electric motor which is mounted on the base 50, and which motor is connected also through a V-belt 59 with a pulley 60, which is keyed to the drive shaft SI of a speed reducer 62 that is mounted on the base 50 adjacent the motor.

The speed reducer 62 has a reduced speed power output shaft on which is mounted a crank 04 for turning movement thereby. A link-arm 65 has one end pivoted to the crank-54 and its opposite end pivotally connected with the lower end of a swinging lever-arm 85. The lower end of the lever-arm 58 is bifurcated to receive therein the adjacent end of the link-arm 65. The lever-arm extends upwardly at the end of the burner and has its upper end pivotally mounted on a support 51 on the burner head 45 for lateral swinging movement in response to the operation of the motor acting on the lever-arm through the link 65.

The lever-arm 66 is also bifurcated at its middle portion, as shown at I3 in Fig. 1, thereby providing an open space in which is located a walking beam I4, pivoted at I5 intermediate its ends to the lever-arm 56. The opposite ends of the walking beam member I4, carry links I6 and TI pivoted thereto. These links I8 and I1 extend transversely of the burner head 45 in opposite directions, and have their outer ends pivotally connected (Fig. 2) at I8, 18, respectively, with crank-arms 80, 8|, keyed to shafts 82, 83 journaled to turn freely in bearings 84, 85, respectively, integral with the burner part 5. Also keyed to the shafts 82, 83 are short crank-arms 85, 81, two crank-arms being provided on each shaft, which crank-arms carry pawls 88, 89, held in engagement with the teeth 31 of the driving rings 3|, 32 by means of springs. On the outer ends of the shafts 82, 83, are keyed crank-arms 92, which carry pawls 94, held in operating engagement with the teeth 4| of the driving ring 39 by means of springs. Crank-arms 92 are shorter than the crank-arms 88, 81, so as to provide for smaller throw of the pawls 94, than of the pawls 88, 89, consistant with the smaller size of the teeth 4! than the teeth 81.

The foregoing structure is setforth more in detail, and claimed, in the co-pending application of Weston M. Fulton, on Burners for solid fuels, Serial No, 546,771.

One or more inlet connections are provided at I03 in the stationary burner grate enclosure, and similar outlet connections I04, leading respectively to the bottom and top portions of the steam or hot water boiler 52. Thus water from the bottom of the boiler will be directed into.

the water passages of the burner enclosure through the connection I 03 where it will be heated and returned to the boiler through the top connection I04.

Referring to Fig. 3, the burner head 05 has integral therewith, a hollow member I05 which is in open communication with the chamber 46 of the burner head so that water can circulate freely therebetween. The member I05 extends throughout the entire length of the interior of the burner, as shown in Fig. 3, and is crescent- ,shaped in cross-section, as shown in Fig. 2. This member I05 is spaced from the interior wall 0 of the grate enclosure to permit the grates 28 and 43 to slide freely through the space between the wall 4 and the member I05. The member I05 preferably is not concentric with the wall 4 of the grate enclosure, the eccentricity being suflicient to make the space between the two increase somewhat as the grates pass around in the direction of the arrow in Fig. 2.

The member I05 has integral with its terminal edges, two channels I06 extending lengthwise thereof, and have channels I01 at opposite ends thereof, in which channels I06, I01 rests the edges of a fire-clay baflie I00. The purpose of this baflle is similar to that described in the co-pend-- ing application of Weston M. Fulton, Serial No. 535,848, filed May 16, 1944, for Burners for solid fuels. The baffle I08 is preferably spacedsomely, the bars,

what from the member I05, as indicated at I to reduce the heat exchange therebetween.

In the operation of the the blower 21 and also the operating parts described above, which rotate the driving rings 3|, 32, and 39. As the driving rings thus rotate in the direction indicated by the arrow in Fig.2, they carry with them the grate-bars 28 and 03, along with the burning fuel that lies on the gratebars, at least within the fuel bed indicated at B in Fig. 2. The grate-bars are loosely supported and are so connected with the driving rings that the driving force applied to the bars tends to push them outward from the axis of rotation to bear against the inner wall 4 of thewater-cooled enclosure. They are thus maintained in firm contact with this cooled surface while they are passing through the region covered by the major burner, the motor drives portion of the fuel bed B in the lower segment of the burner, which is the region in which they 'aresubjected to the most intense heat. I

As the grate-bars 28 are carried forward in the direction indicated by the arrows, they enter the spaced between the water-cooled member I05 and the outer enclosure. As the bars approach the region vertically above the center of rotation, they are free to drop down by gravity onto the peripheral surface of the member I05. Here it will be noted that the action of gravity gradually shifts the grate-bars away from the water-cooled enclosure towards the member I05. Also the bars are relieved of the weight of fuel as they rise above the fuel bed, and hence the driving force is reduced to a minimum, and correspondingly reducing the component of force tending to deflect the grate-bars outwardly. Consequentupon entering the space between the member I05 and the water-cooled enclosure, soon drop by their own weight down onto the periphery of the member I05 and bear thereon in their movement over the upper portion of said member. These bars are then carried around on this member to where they emerge from the space mentioned, and in so doing, reach a region where the bars bear outwardly against the enclosure wall 0. c

It will be noted that the construction and arrangement of the grate-bars and their driving mechanism, as described, cause these grate-bars to be held in contact with the surrounding cooling surface by yielding forces, 1. e., gravity and mechanical power transmitted through two slidably connected surfaces.

Since the curvature of the member I05 is eccentric to that of the enclosure wall, the space therebetween increases from the point where the grates enter this space to the point where they leave it. The object of this arrangement is to prevent any possibility of the grates becoming clogged by any foreign matter which may accidentally exist in the fuel, and which may adhere to the bars and be carried by them into this space. It will be evident from Fig, 2 that any particles small enough to be'carried by the grates through the restricted entrance to this passage, would be carried progressively along to constantly increased freedom of movement so that it could not clog the grates.

The increased size of this grate passage from its entrance to its exit also permits the grates to change their relative relationships moving in a non-circular orbit, and thus free the air spaces 36 between them from small pieces of fuel which may drop therein. It is evident that as each for-- ward moving grate-bar drops down onto the member I05, the space between it and the next adjacent grate-bar, is enlarged somewhat, thus freeing all particles contained in this space.

Furthermore, as th grate-bars move to the exit side of this space, they again change relationships, and finally their relationship is changed for a third'time as they move into and through the fuel bed B, as shown in Fig. 2. This constant shifting action makes thegrate-bars self-"cleaning and has proven from practical tests of the construction to possess great merit. As fuel is fed into the burner at the fuel inlet 54, it drops onto the grates or lower edge portion of the fuel .bed and is carried around by the grate-bars through the fuel bed. It is there supplied with air from the wind-box 25 through the slots 20 and air chambers I0. thence through the openings or slots 36 between the grates into the bed of burning fuel, as indicated by the arrows in Figs. 2 and 3.

The fire-clay baille I08 is similar to the corresponding baiile set forth and claimed in the application. Serial No.,535,848, being used for a similar purpose. Here the baifle has an additional advantage, however, of protecting the grates from the burning fuel. The water-cooled member I05 affords added protection for the grates and also furnishes a relatively cool surface for them to rest upon whilemoving through the upper portion of their path of rotation.

ment through an orbit and adapted to support a fuel bed in the lower portion of said orbit, and a water-cooled bafile extending beneath the grates at the upper region of the orbit and on the opposite side of the orbit from the fuel bed, being transversely curved and having a peripheral surface supporting the grates thereon during movement through the upper portion of the orbit.

2. A burner for solid ture including rotary grates mounted for movement through an orbit and adapted to support a fuel bed in the lower portion of said orbit, and a Water-cooled baiile extending beneath the grates at the upper region of the orbit and positioned between the upper portion of said grates and the lower fuel-supporting portion of said grates, being transversely curved and having a peripheral surface supporting the grates thereon during movement through the upper portion of the orbit, and power means for moving the grates through the orbit and having loose connection with the grates permitting relative transverse movement thereof 3. A burner for solid fuel including rotary grates mounted for movement through an orbit and adapted to support a fuel bed in the lower portion of said orbit, and a fluid-cooled baffle extending beneath the grates at the upper region of the orbit and on the opposite side of the orbit from the fuel bed, said baffle having a surface supporting the grates thereon during movement through the upper portion of the orbit.

' 4. A burner for solid fuel comprising a structure including rotary grates mounted for movement through an orbit and adapted to support fuel comprising a structioned between the upper portion of said grates and the lower tuel-supportingportion of said 5 grates, said baffle having a surface supporting the grates during movement through the upper portion oi the orbit, and power means for moving the grates through the orbit.

WESTON M. FULTON. SIDNEY R. GALYON.

REFERENCES CITED file of this patent:

Number Number 8 UNITED STATES PATENTS Name Date McEwen Mar. 2, 1926 Bouton Oct. 8, 1935 Smallwood v Nov. 18, 1913 Wright Apr. 13, 1943 Davey Mar. 10, 1942 FOREIGN PATENTS Country Date Germany May 2, 1923 Great Britain May 12, 1932 Great Britain July 29, 1926 

